The concept of marking systems for a wide agricultural implements is well known in the art. Typically, during a first pass of the implement, some type of mark is applied to the field either mechanically or chemically to provide a reference mark for the operator to follow on a return pass. The reference mark enables the operator to maintain each pass of the vehicle in the proper position to minimize overlapping or underlapping of the path followed by the implement during a return pass; however, in some applications, visual field markings are inadequate. For example, if the operator is applying chemicals or herbicides to the field on a boom arm extending 60 feet from each side of the tractor, it is difficult for him or her to visually determine exactly where the edge of the previous pass ends with respect to the end of the boom arm which is located lateral to him or her.
Overlapping in applying agricultural chemicals wastes chemical, can harm crops. Underlapping can leave crop gaps in the field which reduces the yield of the crop. Accordingly, the present invention provides an inexpensive system for marking an implement path and remotely determining the position of the implement with respect to the markings on a subsequent pass of the implement.